PCI/AER: Support ACPI HEST AER error sources for PCI domains other than 0

PCI/AER: Support ACPI HEST AER error sources for PCI domains other than 0

In the discussion for this set of patches [link below], Bjorn Helgaas
pointed out that the ACPI HEST AER error sources do not have the PCIe
segment number associated with the bus.  I worked with the ACPI spec and
got this change to definition of the "Bus" field into the recently released
ACPI Spec 5.0a section 18.3.2.3-5:

  Identifies the PCI Bus and Segment of the device.  The Bus is encoded in
  bits 0-7.  For systems that expose multiple PCI segment groups, the
  segment number is encoded in bits 8-23 and bits 24-31 must be zero.  For
  systems that do not expose multiple PCI segment groups, bits 8-31 must be
  zero.  If the GLOBAL flag is specified, this field is ignored.

This patch makes use of the new definition in the only place in the kernel
that uses the acpi_hest_aer_common's bus field.

This depends on 36f3615152c1 ("ACPICA: Add helper macros to extract
bus/segment numbers from HEST table.")

Link: http://lkml.kernel.org/r/1370542251-27387-1-git-send-email-betty.dall@hp.com
Signed-off-by: Betty Dall <betty.dall@hp.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>